In order to obtain a molded product formed by plural kinds of materials different from one another or materials of plural colors different from one another, there is a method of using an injection molding machine including a cavity on a primary side and a cavity on a secondary side (e.g., see Patent Documents 1 and 2). This injection molding machine includes a stationary die plate, a movable die plate that can approach and separate from the stationary die plate, and a rotary die plate provided between the stationary die plate and the movable die plate. Dies are respectively attached to the stationary die plate and the movable die plate. Dies are respective provided on both surfaces of the rotary die plate to be opposed to the die of the stationary die plate and the die of the movable die plate. The rotary die plate is rotatably provided. The rotary die plate is rotated, whereby the respective dies provided on both the surfaces thereof are alternately opposed to the die of the stationary die plate and the die of the movable die plate.
First, in a state in which one die of the rotary die plate is opposed to the die of the movable die plate, first resin is injected to a cavity on a primary side formed between the dies and is pressure-molded. Subsequently, the rotary die plate is rotated with an obtained molded product kept attached to the die of the rotary die plate and opposed to the die of the stationary die plate. Second resin is injected to a cavity on a secondary side formed between the die of the stationary die plate and the die of the rotary die plate and is pressure-molded.
In this way, a molded product formed by the first resin and the second resin having different materials and different colors can be obtained.